05000361/LER-2008-002

LER-2008-002, Disturbance on the Pacific DC Intertie cause offsite power frequency to dip below operability limits

Docket Number
Event date:	5-20-2008
Report date:	6-06-2008
Reporting criterion:	10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident
3612008002R00 - NRC Website

On May 20, 2008, at about 1310 PDT, the offsite power grid connected to San Onofre Nuclear Generating Station (SONGS) experienced a momentary disturbance. Control Room indicators alerted Operators that grid frequency dipped below 59.7 Hz, to about 59.69 Hz. Southern California Edison (SCE) reported this event in accordance with 10CFR50.72(b)(3)(v)(D) (NRC Log No. 44227). The frequency dip at SONGS lasted approximately 10 seconds and was caused by a disturbance on the Pacific DC Intertie line in Oregon.

SCE is submitting this follow-up written report in accordance with 10CFR50.73(a)(2)(v)(D).

During this occurrence, Unit 2 was operating at about 99 percent power; Unit 3 was operating at about 80 percent power.

During the event, both trains of onsite AC sources [EK] on Unit 3 and one train on Unit 2 were available. The size and duration of the frequency dip were small. Consequently, there was little to no safety significance to the event.

There are no corrective actions required at SONGS due to this event.

events.